Subject: [IGSMAIL-0608] IGS Final Orbit Comb (w738-741)
From: Analysis Centre Coordinator
Date: Fri, 20 May 1994 9:34:45 PDT

******************************************************************************
IGS Electronic Mail      Fri May 20  9:34:45 PDT 1994      Message Number 0608
******************************************************************************

Author: Analysis Centre Coordinator
Subject: IGS Final Orbit Comb (w738-741)

*******************************************************************************

IGS Final orbits/clocks completed and put onto CDDIS (Weeks 738, 739, 740, 741)
                                                     ( Feb. 27 - Mar. 26, 1994)
*******************************************************************************

According to the recommendations of the Analysis Centre Workshop the IGS
Rapid Orbits were recomputed using up to date orbits and the final EOP values
of Bulletin B, published by IERS. ( Daily values, page 2 of Bull. B were
used). The EOP were corrected for the difference between the IERS pole series 
and ITRF as published in the IERS 1992 Annual Report (p. II-17, Table II-3),
so both the IGS orbits and associated ERP files are consistent with ITRF92
(current epoch).

We have downloaded all submitted ephemeris and ERP files from CDDIS before the
final orbit/clock combination to ensure that the sets are complete and up to
date. In the final combination we have largely followed the actions taken
during the Rapid orbit generation and since there were very few orbit
resubmissions, both the IGS Rapid  and Final orbits are virtually same except
for the the orientation difference (the current Bull.A and final Bull.B). Orbit
evaluation are also nearly the same, since we used centre specific ERP in
these long arc evaluations. For more information see the corresponding summary
files on CDDIS.

PRODUCTS GENERATED:

The resulting final IGS ephemeris and clocks are in daily files in the SP3
format. The sat. orb. accuracy codes displayed in the headers are based on
weighted RMS for each satellite. Note that each file contains all the submitted
satellites. If satellite or centre had to be excluded from the combination it
is noted in the summary file along with the reason for doing so.

The IGS FINAL ORBIT files generated and uploaded into CDDIS @ NASA/GSFC are:

IGS07380-6.SP3   IGS GPS orbit/clock files for days 0-6, week 0738
IGS07390-6.SP3   IGS GPS orbit/clock files for days 0-6, week 0739
IGS07400-6.SP3   IGS GPS orbit/clock files for days 0-6, week 0740
IGS07410-6.SP3   IGS GPS orbit/clock files for days 0-6, week 0741

IGS07387.ERP    EOP associated with the above orbits (Bull. B aligned to ITRF)
IGS07397.ERP    EOP associated with the above orbits (Bull. B aligned to ITRF)
IGS07407.ERP    EOP associated with the above orbits (Bull. B aligned to ITRF)
IGS07417.ERP    EOP associated with the above orbits (Bull. B aligned to ITRF)

IGS07387.SUM    Complete summary/statistics report
IGS07397.SUM    Complete summary/statistics report
IGS07407.SUM    Complete summary/statistics report
IGS07417.SUM    Complete summary/statistics report

The old Rapid Orbit files have been renamed (on CDDIS) to:
(Note this is temprorary, based on discussions with AC and GB and may be
changed )

IGR07380-6.SP3   Rapid service orbits/clocks for days 0-6, week 738
IGR07390-6.SP3   Rapid service orbits/clocks for days 0-6, week 739
IGR07400-6.SP3   Rapid service orbits/clocks for days 0-6, week 740
IGR07410-6.SP3   Rapid service orbits/clocks for days 0-6, week 741

IGR07387.ERP     Rapid service EOP associated with the above orbits (Bull A)
IGR07397.ERP     Rapid service EOP associated with the above orbits (Bull A)
IGR07407.ERP     Rapid service EOP associated with the above orbits (Bull A)
IGR07417.ERP     Rapid service EOP associated with the above orbits (Bull A)

IGR07387.SUM     Rapid service complete summary/statistic report 
IGR07397.SUM     Rapid service complete summary/statistic report 
IGR07407.SUM     Rapid service complete summary/statistic report 
IGR07417.SUM     Rapid service complete summary/statistic report 

 *****************************************************************************

REMARKS/CORRECTIONS:

None